Numerous devices are available in the prior art for providing accurate linear measurements. Height gauges are available to provide the height of an article. Dial gauges, Digimatic.TM. indicators, and linear gauge systems are used to precisely measure the thickness or height of an article. Linear and X-Y coordinate location and displacement measuring systems are available to accurately measure the linear displacement from a particular coordinate and the exact position of an article or particular features on an article.
Many of the systems in use today for providing a linear measurement include a housing having a measuring member and a spindle slidably mounted on the housing. The spindle is coupled between the measuring member and the article to be measured. A bushing mounted on the housing and surrounding the spindle is typically used to ensure that the spindle slides smoothly in the housing.
The conventional bushing and spindle arrangement known in the prior art is suitable for accurate measurements in the millimeter range. However, the accuracy of measurements made using a bushing-mounted spindle can be adversely affected if the bushing does not adequately limit the spindle to movement along a single linear axis. If the spindle pivots as it slides in the housing, movement of the end of the spindle contacting the object to be measured is not accurately transmitted to the measuring member. As a result, conventional bushing and spindle configurations do not have sufficient accuracy for use in a linear gauge in the micron or submicron range. If measurement in the micron or submicron ranges is desired, a more expensive and complicated system must be used in place of the linear gauges having a bushing and spindle available in the prior art.